fix broken link

As reported by CI, this link was broken sometime in the last couple PRs.  Fixing.

product_design/how_we_write_user_stories.md

@@ -47,7 +47,7 @@ When the Designer has enough context on the problem (from the speclet and discov
 Product Manager creates the Epic(s) and possibly shell user story tickets in Jira. 
 Follow [this guidance](../product_design/structuring_epics_stories_bugs_and_tasks.md#epics) on epics.<br>
 4. **Add User Stories to the Epic**<br>
-When designs are agreed on, the Designer prepares the designs for handoff and [writes detailed user stories based on the designs](../product_design/structuring_epics_stories_bugs_and_tasks.md##user-stories). *If the epic doesn’t have a user interface, it may be more appropriate for the Lead Engineer to write the user stories.*<br>
+When designs are agreed on, the Designer prepares the designs for handoff and [writes detailed user stories based on the designs](../product_design/structuring_epics_stories_bugs_and_tasks.md#user-stories). *If the epic doesn’t have a user interface, it may be more appropriate for the Lead Engineer to write the user stories.*<br>
 5. **Preview stories**<br> 
 The Product Manager, Designer, and Lead Engineer review all stories before Storytime and estimation.<br>
 6. **Initial prioritization**<br>